2-chloro displacement

More recently, thianthrene was synthesized from 1,2-dichlorobenzene with hydrogen sulfide at 550 C. This method is of particular interest since it demonstrates thianthrene formation in high yields from chloro-displacement reactions, and more importantly indicates thermal stability of the thianthrene nucleus well into the upper temperature range for high-performance polymers. 

It is possible to prepare 1-acetoxy-4-chloro-2-alkenes from conjugated dienes with high selectivity. In the presence of stoichiometric amounts of LiOAc and LiCl, l-acetoxy-4-chloro-2-hutene (358) is obtained from butadiene[307], and cw-l-acetoxy-4-chloro-2-cyclohexene (360) is obtained from 1.3-cyclohexa-diene with 99% selectivity[308]. Neither the 1.4-dichloride nor 1.4-diacetate is formed. Good stereocontrol is also observed with acyclic diene.s[309]. The chloride and acetoxy groups have different reactivities. The Pd-catalyzed selective displacement of the chloride in 358 with diethylamine gives 359 without attacking allylic acetate, and the chloride in 360 is displaced with malonate with retention of the stereochemistry to give 361, while the uncatalyzed reaction affords the inversion product 362. 

Substitution reactions on dialkyl peroxides without concurrent peroxide cleavage have been reported, eg, the nitration of dicumyl peroxide (44), and the chlorination of di-/ fZ-butyl peroxide (77). Bromination by nucleophilic displacement on a-chloro- or a-hydroxyalkyl peroxides with hydrogen bromide produces a-bromoalkyl peroxides (78). 

There is a large variety of chloro or fluoro substituted heterocyclic rings which undergo X displacement by cell-0. Vinyl sulfones are usually generated under alkaline conditions from P-sulfatoethjisulfones,... 

The ease of displacing a chloro, bromo or iodo substituent in comparable pyrimidines by aminolysis is disappointingly similar. Using 2-halogeno-4,6-dimethyl- and 4-halogeno-... 

Halogen atoms on benzazole rings can be activated toward nucleophilic displacement by electron-withdrawing groups. Thus azide ion displaces chlorine from 5-chloro-4-nitro- and 4-chloro-7-nitro-benzofuroxan (65JCS5958). 

Chloro-5-arylisoxazoles undergo nucleophilic displacement with alkoxide ion. Halogen atoms in the 5-position of the isoxazole nucleus are readily displaced if an activating group is present in the 4-position (63AHC(2)365). 

Imtdazo[4,5-d]pyridaztne, l-benzyl-4,7-dtchloro-nucleophtlic displacement reactions, 5, 629 Imidazo[l,5-6]pyridazine-5,7(3H,6H)-dione, 4-acetyl-2-phenyl-synthesis, 5, 651 Imidazo[l, 2-6]pyridazines reactions, 5, 628 synthesis, 5, 650 Imidazo[ 1,5-6]pyridazines synthesis, 5, 651 Imidazo[4,5-c]pyridazines reactions, 5, 628-629 synthesis, 5, 651 Imidazo[4,5-d]pyridazines reactions, 5, 629 synthesis, 5, 436, 468, 651-652 3H-Imidazo[l,2-6]pyridazin-2-one, 6-chloro-3-dichloromethylene-synthesis, 3, 355... 

H-Pyrimido[l, 2-6]pyridazin-2-one, chloro-nucleophilic displacement reactions, 3, 343 2H-Pyrimido[l,2-6]pyridazin-2-one, 7-chloro-synthesis, 3, 354... 

Primary alkyl chlorides are fairly stable to fluorine displacement. When fluorinated, 1-chloropropane is converted to 1-chloroheptafluoropropane and 1-chloto-2-methylbutane produces 39% l-chlorononafluoro-2-methylbutane and 19% perfluoro-2-methylbutane. Secondary and tertiary alkyl chlorides can undergo 1,2-chlorine shifts to afford perfluonnated primary alkyl chlorides 2-Chloro-2-methylpropane gives l-chlorononafluoro-2-methylpropane, and three products are obtained by the fluorination of 3-chloropentane [7] (equation 1). Aerosol fluorina-tion of dichloromethane produces dichlorodifluoromethane which is isolated in 98% purity [4 (equation 2). If the molecule contains only carbon and halogens, the picture is different. Molecular beam analysis has shown that the reaction of fluorine with carbon tetrachlonde, lodotrichloromethane, or bromotrichloromethane proceeds first by abstraction of halogen to form a trichloromethyl radical [5]... 

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